Nuclear power plants and thermal power plants use water as an energy transfer medium to obtain electric energy from nuclear power energy or fossil fuels. In general, water/vapor circulation systems in power plants include vaporizing water to rotate turbines and generate electricity, and condensing the vapor back into water for recirculation.
At that time, various parts of such systems may be corroded and damaged by the water. Thus, some chemicals, such as pH adjusting agents and chemical potential adjusting agents, may be added to inhibit corrosion of various metals electrochemically.
The water/vapor circulation systems of nuclear power plants and thermal power plants are provided with ion exchange resin towers, and thus not only a trace amount of impurities but also such chemicals added for inhibiting corrosion are removed. Therefore, it is required to remove the chemicals from the ion exchange resin and inject them back to the ion exchange resin from an external source in every water/vapor circulation cycle.
Since some of the above mentioned chemicals are highly volatile materials that are emitted to the air during their treatment, they may be easily treated by a simple physical process. However, other chemicals may exist in water to cause an increase in biochemical oxygen demand (BOD) and total nitrogen concentration specified by environmentally permissible emission standards. In this case, it is not possible to satisfy standards for effluents.